Face encoding has been experimentally differentiated from encoding of other visual patterns in three respects: in terms of certain psychophysical effects, in terms of neural substrates, and in terms of a characteristic course of development. Part I of the proposal pursues the information processing implications of these differentiations. A parametric study examines the efficiency of the encoding device, and charts its developmental course. Studies of the ability to judge age, sex, and emotion from faces complement studies of judgments of personal identity in constraining models of face encoding. Hypotheses as to the special problems faces pose an encoding device are proposed to account for the three respects in which face encoding seems special. These hypotheses are tested in stimulus domains chosen to contrast or match faces in relevant respects. Part II of the proposal concentrates on development alone. Two maturational components to the development of face encoding skills are hypothesized and two different methods are proposed for evaluating these hypotheses. The overall goals of this research are twofold. We wish to contribute to the understanding of the prodigious human capacity for encoding and recognizing faces. We also want to explore the consequences of adopting what we have called a "modular" approach to cognition. Our assumption is that not all visual pattern recognition devices are alike, and the ways in which they differ may reveal important insights into cognitive processes and cognitive development.